Originally Posted by NWBasser
Reply With QuoteThe EL84 tubes are just labeled tube 3 and 4 in the schematic there are just two EL84s on the schematic that I see. Being that there are op amps on the +/-15 volt supplies in the signal chain all over the amp those supplies are probably OK. There is an adjustment pot PT110 labeled SYM adjust you could note the current position of the pot and dial it back and forth a few times then back to its original position. This pot looks to be to center the operating point of the two transistors gain stage of T4 and T5 for symmetrical clipping. With a little luck maybe the wiper has a bad contact and exercising it will clear it up. One thing the reverb signal will do is to increase the peak to peak signal when in phase with the clean signal so maybe the SYM adjust will have an effect. I think the schematic is in error on where it shows the reverb return signal and feedback connection because in a simulation that setup would not work. Looking at the schematic there is a master control as well as lead master, clean volume and tone controls. You could try dialing the clean volume back and turning the master up in case it is clipping in the preamp sections before the power section that is the cause of the problem. If the problem is due to overdriving the reverb tank R48 the 22 ohm 1 Watt resistor could be doubled to 44 ohms to reduce the current on the input transducer of the reverb tank.
